doc: clarify task name

tasks/install_packages.yml

@@ -4,7 +4,7 @@
   when: ( ansible_os_family == 'RedHat' ) and
         ( ansible_distribution_major_version == "7" )
 
-- name: install RedHat packages
+- name: install packages required by ExLibris
   yum:
     name: "{{ redhat_packages }}"
     state: present